Commercial crops are often the targets of attack by invertebrate pests such as insects. Compositions for controlling insect infestations in plants have typically been in the form of chemical insecticides. However, there are several disadvantages to using chemical insecticides. For example, chemical insecticides are generally not selective, and applications of chemical insecticides intended to control insect pests in crop plants can exert their effects on non-target insects and other invertebrates as well. Chemical insecticides often persist in the environment and can be slow to degrade, thus potentially accumulating in the food chain. Furthermore the use of persistent chemical insecticides can result in the development of resistance in the target insect species. Thus there has been a long felt need for more environmentally friendly methods for controlling or eradicating insect infestation on or in plants, e. g., methods which are species-selective, environmentally inert, non-persistent, and biodegradable, and that fit well into pest resistance management schemes.
RNA interference (RNAi, RNA-mediated gene suppression) is an approach that shows promise for use in environmentally friendly pest control. In invertebrates, RNAi-based gene suppression was first demonstrated in nematodes (Fire et al., (1998) Nature, 391:806-811; Timmons & Fire (1998) Nature, 395:854). Subsequently, RNAi-based suppression of invertebrate genes using recombinant nucleic acid techniques has been reported in a number of species, including agriculturally or economically important pests from various insect and nematode taxa, such as: root-knot nematodes (Meloidogyne spp.), see Huang et al. (2006) Proc. Natl. Acad. Sci. USA, 103:14302-14306, doi:10.1073/pnas.0604698103); cotton bollworm (Helicoverpa armigera), see Mao et al. (2007) Nature Biotechnol., 25:1307-1313, doi:10.1038/nbt1352; Western corn rootworm (Diabrotica virgifera LeConte), see Baum et al. (2007) Nature Biotechnol., 25:1322-1326, doi:10.1038/nbt1359; sugar beet cyst nematode (Heterodera schachtii), see Sindhu et al. (2008) J. Exp. Botany, 60:315-324, doi:10.1093/jxb/ern289; mosquito (Aedes aegypti), see Pridgeon et al. (2008) J. Med. Entomol., 45:414-420, doi: full/10.1603/0022-2585%282008%2945%5B414%3ATAADRK %5D2.0.CO %3B2; fruit flies (Drosophila melanogaster), flour beetles (Tribolium castaneum), pea aphids (Acyrthosiphon pisum), and tobacco hornworms (Manduca sexta), see Whyard et al. (2009) Insect Biochem. Mol. Biol., 39:824-832, doi:10.1016/j.ibmb.2009.09.00; diamondback moth (Plutella xylostella), see Gong et al. (2011) Pest Manag. Sci., 67: 514-520, doi:10.1002/ps.2086; green peach aphid (Myzus persicae), see Pitino et al. (2011) PLoS ONE, 6:e25709, doi:10.1371/journal.pone.0025709; brown planthopper (Nilaparvata lugens), see Li et al. (2011) Pest Manag. Sci., 67:852-859, doi:10.1002/ps.2124; and whitefly (Bemisia tabaci), see Upadhyay et al. (2011) J. Biosci., 36:153-161, doi:10.1007/s12038-011-9009-1.